Color photography with key print



UNITED'STATES P'lENT OFFICE COLOR PHOTOGRAPHY WITH KEY PElHW Joseph A. Ball, Los Angeles, Calif., assignor to Technicolor Motion Picture Corporation, Boston, Mass, a corporation of Maine Application July 21, 1933, Serial No. 681,458

8 Claims. (01. 95-2) In the art of color photography it is very difing description of an embodiment of the inficult or perhaps impossible to attain with two vention illustrating its genus. The description or more superposed colored prints-alone the whole refers to a drawing, in which the figure reprerange of neutral tones, the darker portions of sents a fiow diagram schematically representing the color prints especially beingunsatisfactory the process according to the invention. 0

obtained only by superposing prints in colored Although the new process can be used-with a inks or dyes. It is, therefore, general practice different number of color records, in the emto print with the color positives a so-called key bodiment to be described three color separation print in black or gray, which imparts vigor to negatives B, G, R, representing the blue, green,

10 the reproduction, and can also be relied on to and red components or color aspects of the ob- 5 supply details which cannot always be fully ject field, or three color records and one key brought out with color prints alone. negative, are taken, for example by means of an Similar problems are present in color sinearrangement described in my Patent No.

I matography, and it has therefore been proposed 1,889,030 of November 29, 1932, for Multicolor to supplement positive color films with key prints. photography with bipacks, and developed and fin- 7 However, most techniques of making films in natished in the customary manner. From any of ural colors involve quite complicated treatments these prints, or from a separately exposed key in various baths which cause the films to change print record, or from all or any of the three color their dimensions, thereby making it difficult to records combined with each other and/or the maintain the precise register between the various key negative, an auxiliary positive is made. In 7 prints, which is an indispensable prerequisite for the present embodiment as illustrated inthe the successful production of composite color films. drawing, a composite key record positive KP is This difficulty is also present in processes empreferably obtained by simultaneously or conploying positive gelatine matrices made from the secutively exposing a positive film F to different 26 original color aspect negatives which are dyed. ,color aspect negatives with the aid of a projec- 30 and either used directly or for making so-called tion printer, care being of course taken that the imbibition prints, whereby the dye is transexposures are in exact register. ferred to positive blank films which receive in From the composite positive, an auxiliary negsuperposition the various dye imprints from the ative, herein referred to as key negative KN, is

30 matrices and whichmay be provided, prior to then printed on film FN, preferably on a prothe dye transfer, with a photographically projection printer for reasons which will become apduced black and white silver key print. It has, parent hereinafter. however, been found that films may shrink as The key negative KN is then copied onto the well as expand during the treatment they unfinal positive film F. The printing preferably 35 dergo according to this method, so that key print takes place on a contact printer of conventional and color prints cannot be properly correlated. design. The final positive is then developed and It is, therefore, the principal object of the fixed in the customary manner, and bears now present invention to provide a method permita series of silver key records K.

ting the correct registration of a photographic In the meantime, gelatine matrices Y, M, C,

., 40 key print with color reproductions in dye. Anhave been. made from the three color separation other object is to provide a process whereby durnegatives B, G, R, respectively. These matrices the manipulation of films with records of may be of any suitable type, either fiat of the components of the final positive print, the size so-called hydrotype kind, or gelatine reliefs, of certain records can be're'ctified in-order to preferably made by the process described and 5 compensate for deformations of the strip mateclaimed in Patent No. 1,919,673, granted July 25,

rial which supports the emulsion material dur- 1933. These matrices are then passed through ing the processing of the various component baths where they imbibe dyes of hues complerecords. mentary to the taking colors blue, green, and red,

In still another aspect, the invention provides namely, yellow, magenta, and cyan respectively,

0 a method for compensating film record size difin amounts varying with the hardness of the ferences by means of projection printing, by gelatine and/or the height of the relief reprepermitting the copying of the final key posisenting the color aspect records. The matrices tives by contact printing. are then consecutively brought into pressurable These and other objects and advantages of contact with the positive film F, in correct regis- I vU55 the invention will be apparent from the followter with the key print K already contained in the no gelatine emulsion of film F, preferably on a machine according to Patent No. 1,707,710 of April 2, 1929 to Daniel F. Comstock, for Method and apparatus for imbibition printing, where the dyes are transferred from the matrices to the positive film. After leaving the machine, film F has impressed thereon a record P comprising the positive key print K and the positive color record Y M, Qand is ready to be shown with the aid 'of any-conventioual motion picture projector.

The process as above described encounters the difliculty that commercially available films under-Q go considerable changes in dimensions during the various treatments involving the wetting and drying of the film base. Especially the film stock used for making the color record matrices changes its dimensions during the wetting process in the dye tanks (step W of the drawing), either by expansion or contraction, depending on the nature of the material used. Whereas the longitudinal change in dimension can in most cases be neglected or taken care of by the registering organs of the transfer apparatus, for example the steel pin belt of the imbibition machine according to the above identified patent, it becomes necessary to compensate for the lateral shrinkage or expansion of film in order to obtain the necessary perfect register between key print and color prints. It wilLbe understood, however, that both longitudinaf'and lateral .s'hri'pkages and/or expansions can be taken care of bythe present method.

According tothis method, an optical compensator or anamorplioser of suitable design, butpreferably of the type described in divisional application Serial No. 706,028, filed Jan. 10, 1934, is employed with one of ,the projection printers used at steps N, S or T of the process, as indicated in the drawing. Preferably, step? is utilized for this purpose, since it is at that time possible to compensate for dimensional changes in any of the steps N and S, where such changes are most likely to occur. This arrangement has the further advantage that it requires the least possible number oi compensating projection printing steps and permits the printing of the final key positive on a contact printer. Since the printing steps N, S, T have to be performed only once for each negative record, but the printing of the final key must be repeated for each positive film, it'is of importance that the more complicated and expensive projection printing is confined to the first mentioned steps, whereas the simpler and less expensive contact printing is preferable for the many times repeated step V. Further, each of steps N and S actually involves, in the preferred embodiment of the process. three printing steps which. if one of these steps were utilized for optical compensation, would involve a threefold increase of the possibilities of error of compensation, whereas the introduction of a composite positive and a key negative according to the present invention permits compensation during a. single step with the resulting advantages.

Since the changes of film dimensions vary a great deal dependent on a large number of circumstances, and may even change from shrinkage to expansion and vice versa, it is very important to employ a compensating device which can be easily and exactly adjusted for varying degrees and directions of changes in film dimensions. A new compensator arrangement especially suited for this purpose will now be described as employed for lateral compensation, although it is understood that it may be analogously used for longitudinal compensation, or that two compensations may be used in series in one or dififerent projection printers for compensation in both directions.

It will now be evident that by employing a device permitting dimensional correction of the record in cooperation with lens system L of the projection printer used for carrying out the compensating printing step or steps (for example, step T, or step S), the film shrinkage can be compensated for in a simple manner effective in varying conditions, and that, with the method according to the present invention, it is always possible to obtain precise register between a photographic key print positive and a series of superposed color records.

It will be further evident that, if one color rec- 0rd or an initially exposed key negative is employed for making the key print, it will not be necessary to make a composite key positive. However, although it would be feasible to print directly from the original key negative onto the positive film F, compensating each time for dimensional changes, it will be nevertheless preferable to make an auxiliary key positive corresponding to KP, and therefrom a duplicate negative KN, and to compensate during the printing of KN from KP.

It should be understood that the present disclosure is for the purpose pf illustration only and that this invention includes all modifications and equivalents which fall within the scope of the appended claims.

I claim:

1. The method of producing photographic films in natural colors which comprises the taking of, negative color separation records, the making of a gelatine matrix from each negative record, the printing of an auxiliary positive key record, the printing of an auxiliary key negative from said auxiliary positive, the photographic copying of said key negative upon the emulsion of a positive film and the printing by imbibition of color positives from'said matrices upon said positive film in register with one another and with said photographic copy.

2. The method of producing photographic films in natural colors which comprises the taking oi negative color separation records, the making of a gelatine matrix from each negative record, the photographic printing of an auxiliary positive key record, the photographic printing of an auxiliary key negative from said auxiliary positive, the printing of a photographic copy of said key negative upon the emulsion of a positive film, the printing by imbibition of color positives from said matrices upon said positive film and, during one of said photographic printing steps, the compensation with optical means of film distortions occurring during other steps of the process, in order to obtain register between said photographic copy and said color positives.

3. The method of producing photographic films in natural colors which comprises the taking of negative color separation records, the making of a gelatine matrix from each negative record, the printing of an auxiliary positive key record, the printing upon a projection printer of an auxiliary key negative from said auxiliary positive by optically compensating for record distortions occurring during other steps of the process, the printing of a photographic copy of said key negative upon the emulsion of a positive film and the printing by imbibition of color positives from said matrices upon said positive film, in register with oneanother and with said photographic copy.

4. The method of producing photographic films in natural colors which comprises the taking of negative color separation records, the making of a gelatine matrix from each negative record, the printing of an auxiliary positive key record, the printing of an auxiliary key negative from said auxiliary positive by changing the lateral dimensions of the key record, the photographic copying of a black and white key positive from said key negative uponthe emulsion of a. positive film and the printing by imbibition of color positives from said matrices over said key positive, said change of dimensions being adjusted to provide register between said key positive and said color positives.

5. The method of producing photographic films in natural colors which comprises the taking of negative color separation records, the making of a gelatine matrix from each negative record, the printing of a composite positive from said negative records, the printing of an auxiliary key negative from said positive, the photographic copying of said key negative upon the emulsion of a positive film and the printing by imbibition of color positives from said matrices upon said positive film in register with one another and with said photographic copy.

6. The method of producing photographic films in natural colors which comprises the taking of negative color separation records, the making of a gelatine matrix from each negative record, the

' photographic printing of a composite positive from said negative records, the photographic printing of an auxiliary key negative from said positive, the printing of a photographic copy of said key negative upon the emulsion of a positive film, the printing by imbibltion of color positives from said matrices upon said positive film and, during one of said photographic printing steps, the compensation with optical means of film distortions occurring during other steps of the process, in order to obtain register between said photographic copy and said color positives.

7. The method of producing photographic films in natural colors which comprises the taking of negative color separation records, the making of a gelatine matrix from each negative record, the printing of a composite positive from said negative records, the printing upon a projection printer of an auxiliary key negative from said pos itive by optically compensating for record distortions occurring during other steps of the process, the printing of a photographic copy of said key negative upon the emulsion of a positive fllrn and the printing by imbibition of color positives from said matrices upon said positive film, in register with one another and with said photographic copy.

8. The method of producing photographic films in natural colors which comprises the taking of negative color separation records, the making of a gelatine matrix from each negative record, the printing of a composite positive from said negative records, the printing of an auxiliary key negative from said positive by changing the lateral dimensions or the key record, the photographic copying of a black and white key positive from said key negative upon the emulsion of a positive film and the printing by imbibition of color positives from said matrices over said key positive, said change of dimensions being adjusted to provide register between said key positive and said color positives.

JOSEPH A. BALL. 

